A hamstring strain is a common injury characterized by the tearing or stretching of the hamstring muscles at the back of the thigh. This injury often occurs during activities that involve sprinting, jumping, or sudden stopping. Symptoms may include pain, swelling, bruising, and difficulty straightening the leg. Treatment typically involves rest, ice application, compression, and elevation (RICE protocol), along with gentle stretching and strengthening exercises. In severe cases, physical therapy and a gradual return to activity may be recommended for full recovery.